1. Field of the Invention
The present invention relates to a high dynamic range image, and more particularly, to a method and system of generating a high dynamic range image corresponding to a specific scene.
2. Description of the Prior Art
In image processing technical fields, the ratio of the highest luminance to the lowest luminance in a scene is defined as a dynamic range of the scene. Typically, the dynamic range of the real world is over 50,000:1, and the dynamic range of the human vision system (HVS) is over 10,000:1. Moreover, in some specific lighting condition, human eyes can differentiate some 10,000 colors. Thus, human eyes can detect different luminance in the real word to a fairly satisfactory degree.
Image capturing devices (such as cameras) or image display devices (such as computer displays) commonly used for processing images, however, have a dynamic range far less than the dynamic range of the real world. Therefore, those image devices are unable to capture or display details of high luminance (i.e. over-exposure) or low luminance (i.e. under-exposure) parts in a scene in some condition. For example, an image capturing device or an image display device having a dynamic range of 255:0 may treat all pixels in a high luminance part in a scene as white pixels having grayscale values of (255, 255, 255), or treat all pixels in a low luminance part in a scene as black pixels having grayscale values of (0, 0, 0). In other words, those image devices are unable to record details of high luminance or low luminance parts in a scene.
Generally, an image having a high dynamic range is called a high dynamic range (HDR) image. Presently, there is no simple and direct way to capture or display an HDR image. Therefore, an alternative method to execute multiple exposures in a scene to capture a plurality of low dynamic range (LDR) images and then combine the LDR images into an HDR image of the scene is provided.
Traditionally, multiple exposures are executed in a scene to capture a plurality of LDR images until the amount of LDR images is sufficient to generate a satisfactory HDR image, thereby consuming a lot of shooting time and storage space for the LDR images.